Supercharger compression temperature control system



une 2i, 1949. H. T. sPARRow SUPERCHARGER COMPRESSION TEMPERATURE CONTROL SYSTEM Filed April 28, 1945 l. iig,

Patented June 2l, 1.949

SUPERCHARGER COMPRESSION TEMPERA-l TURE CONTROL SYSTEM Hubert T. Sparrow,

Minneapolis, Minn., assignor to MinneapolisvHoneywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application April 28, 1945, Serial No. 590,819

12 Claims. 1

This invention relates to electrical control systems.

The invention more particularly relates to improvements in control systems for use in connection with the air induction system of an aircraft engine. Related systems for controlling the intake manifold or induction system pressure of such engines are disclosed in my co-pending application Serial No. 474,378, led February l, 1943, and in the co-pending application of Hubert T. Sparrow and Robert J. Kutzler, Serial No. 486,992, filed May 14, 1943, now Patent No. 2,466,282, to which attention is invited for comparative purposes.

The primary object of my present invention is to improve the operation of such systems by the addition thereto of control means of the following nature. A common form of induction system for an aircraft engine includes a compressor for delivering the air to the intake manifold and a turbine for driving the compressor, said turbine being driven by the exhaust gases from the engine. To control the pressure of the air admitted to the manifold the speed of the compressor is regulated by positioning a waste gate which varies the eliect of the exhaust gases upon the turbine and hence the speed thereof. For positioning this waste gate, a control system is used wherein a reversible Waste gate positioning motor is controlled to vary the position of the waste gate, and this motor is caused to rotate in proper direction by an electronic amplifier the operation of which is a function of the pressure in the intake manifold. A manual control is provided for selecting the pressure to be maintained after which the system functions to maintain that; pressure within close limits.

The compression of the air for supplying the intake manifold, or to the carburetor, naturally causes this air to be heated, the degree to which the air temperature is raised depending of course on the temperature of the air supplied to the compressor and the rate at which the compressor is operated. Under most conditions, and particularly when the aircraft is flying at high or usual altitudes, the heat of compression is so great that a cooling device. commonly called an after cooler, is arranged at the high pressure side of the compressor and fresh airis taken into such cooler and passed in heat exchanging relation to the compressed air as it flows toward the carburetor and manifold, after which the cooling air is discharged to the atmosphere. However, in flying at the extremely high altitudes now possible, the low air temperatures frequently cause 2 icing conditions at'the carburetor and for this reason the air intake for the after cooler is provided with a damper which, when closed, cuts oil? this air permitting the heat of compression to raise the temperature of the air supplied to the carburetor and so eliminate such tendency toward the formation of ice. At present, this damper controlling the after cooler is manually controlled. It will be obvious from the above that a very substantial range of variation is permitted in the temperature plied to the engine.

of the air being sup- Under some conditions, the air may, despite the closure of the after cooler, become so low as to cause icing. Furthermore, regardless of whether icing occurs or not, the variation in temperature renders it more diiiicult to control the engine since the power delivered by the engine is dependent upon the temperature of the air entering the intake manifold.

My invention has as its object to provide a control system for maintaining the temperature of the air entering the intake manifold at a substantially constant temperature.

Another object of my invention is to provide means for so controlling the temperature of the air entering the carburetor that icing will be prevented.

Another object of my invention is to control the throttle position in accordance with the temperature of the air between the after cooler and carburetor and in interrelation with the positioning of the waste gate in such manner that, with the damper fully closed, the necessary heat of compression to raise the air temperature to the required level will be supplied by partially closing the throttle, which action in reducing the manifold pressure, causes the waste gate to be moved toward a closed position to build up this pressure again to the selected value. The resulting increased speed of the turbine and compressor will then raise the heat of compression and temperature of the air supplied to the carburetor. 'I'hisis the typical low altitude operation of the system but this "overlapping control of the throttle and waste gate will be maintained only to a point at which the carburetor air reaches the control point after which the after cooler damper will be gradually opened in order to prevent the temperature form exceeding the desired value as higher altitudes are reached and more supercharging is required.

My invention has as a further object the provision of means for safeguarding the operation at low altitudes in the winter months. With the air effective horsepower of the atmosphere and wherein is located a valve,

at the intakes at a very low temperature it is obvious that, during the aforesaid overlapping control cycle, it is possible that the closing of the throttle and increased speed of the turbine and' compressor might call for the closing of the waste gate to a point whereat the exhaust back pressure would rise above` a value permitting elcient functioning of the engine. I therefore provide means responsive to the exhaust pressure for automatically running the throttle toward the open position when this pressure exceeds the safe value and thereby causing the waste gate to open slightly and reduce the back pressure.

With these and other objects in view, my invention resides in the novel system and arrangement of the parts thereof as hereinafter fully set forth and claimed.

The drawing is a diagrammatic view illustrating the application of my complete control system to an aircraft engine and its component parts. i

Referring now more Aparticularly to the drawing I have shown therein, in block diagram form,

an aircraft engine I0 of the conventional internal combustion type, having an intake manifold II and exhaust manifold I2. The air to support combustion is taken from the atmosphere at an intake I3 and enters a compressor I4, commonly called the supercharger, from which it emerges under compression into a duct I5 leading to a carburetor I6 at the inlet of which there is a throttle I1. From the carburetor, the mixture of fuel and air is fed into another compressor I3 and thence into the intake manifold II. The latter compressor I3 is directly driven from the engine, as indicated at I9, and hence compresses the mixture at a rate dependent wholly upon the speed of the engine. V

The compressor I4 is driven by a turbine 29 to which the exhaust gases emerging from exhaust manifold I2 are led through a duct 2I, and from which the gases are discharged at 22. Extending from the duct 2I is a br-Pass duct 23 leading to commonly termed the waste gate, indicated at 24. Obviously. when the Waste gate 24 is open, the resistance to passage of the exhaust gases through the by-pass duct 23 will be less than the resistance through lthe turbine 20 and the gases will therefore escape with little eiect on the turbine. As the waste gate is progressively closed, more and moreV of the gases will be diverted through the turbine causing it to rotate at increasing speeds, and of course increasing the speed and compression ratio of the supercharging compressor I4. The position of the waste gate is thus seen to control the pressure of the air sup- An after cooler 25 is provided in the duct I5 and fresh air is taken from the atmosphere through an intake 26 .and passed through the after cooler in heat exchangingrrelation to the compressed air owing along the duct, the spent cooling air. being then discharged at 21. The air is taken into the intake 26 through a scoop (not shown) so locatedron the aircraft that the air will be rammed into and through the cooler as a result of the movement of the'. aircraft and a damper or valve member 23 is located in the intake to control the amount of air passed through the cooler. This damper thus controls the cooling effect on the carburetor air, increasing the cooling to overcome the heat of compression ocplied to the carburetor I6.

curring in the compressor I4 when the damperis opened, and decreasing the cooling effect as the damper is closed.

The waste gate 24 is positioned by a reversible motor 29 through a gear train 30, the motor being of the split-phase type having a pair of eld windings 3l and 32, which are spaced ninety electrical degrees apart, and an armature 33. The ileld winding 3lv isenergized from the secondary winding 34 of a transformer 35 and the energizing circuit may be traced from the upper terminal of the secondary winding 34 through a phasing condenser 31, a conductor 36, field winding 3l and a conductor 33 back to the lower terminal of winding 34. y

The other field winding` 32 of the motor 29 isenergized by and under control of an amplifier 39 having output terminals 40 and 4I connected by conductors 42, 33, and 43, respectively to the ends of the winding 32'. The amplifier 39 is supplied with energy from a secondary winding 44 on the transformer 35 to which the amplifier is connected by conductors 45. The transformer 35 comprises a primary winding 93 in addition to the secondary windings 34 and44, previously referred to. The primary winding 93 is connected to any suitable source of power (not shown).

The amplifier 39 has a pair of input terminals 46 and 41 and operates in such manner as to energize the motor field winding 32 with an alternating current the phase angle of which, with respect to the current in field winding 3l is determined by the phase of a signal potential applied to the input terminals. This amplifier, as well as others hereinafter described, may be of any suitable type operative as described. A typical ampliiier of this type is that disclosed in Figure 1 yof the co-pending application of Albert P. Upton, Serial No. 437,561, filed April 3, 1942, now Patent No. 2,423,534..

i, It is evident that if the current in the motor field winding 32, due to the phase of the signal at the amplifler input, leads the current supplied the other field winding 3| by the transformer 35 by ninety electrical degrees, the motor will rotate in one direction whereas, if this current in the winding 32 lags the currentv in winding 3| by the same degree, due to a reversal in phase of the amplifier exciting signal, the motor will rotate ln the opposite direction. The phase angle of the amplifier signal input is thus seen to control the positioning of the waste gate 24 by the motor 29.

The signal potential applied to the amplifier 39 is determined by the electrical conditions in a compound network which consists of three series connected networks 43, 49, and 50. The circuit from amplifier input terminal 46 may be traced through a conductor 5I, the rst network 48, a conductor 52, the second network 49, a conductor 53, the third network 50 and a conductor 54 back to the input terminal 4l.

The networkI 43 -comprises a transformer secondary winding 55 across the terminals of which is connected a slidewire resistance 56 by means of conductors 51 and 58. The aforesaid conductor 5I is connected to a slider 59 which is arranged to traverse the resistance 56 under control of a knob 60, this resistance and slider constituting a control point adjuster 6I for selecting the intake manifold pressure. Another resistance 62 has its terminals connected across one half the transformer winding 55 by conductors 63 and 64, one of which is connected to the lower end of the winding and thev other to a center tap on the winding. A slider 65 co- Aaragon;

operates with the resistance I2 to form a calibrating potentiometer and the conductor 82 is connected to this slider.

The center tap of the transformer winding 55 is connected by conductor 88 to the center of the resistance 88 in order to provide a more tance 81 and together with this resistance forms a rebalancing or waste gate follow-up vpotentiometer. The slider 92 is positioned by the motor' .29 through the gear train 88 as the waste gate uniform potential gradient across resistor 58.

This connection does not otherwise affect the operation of this network.

The network 49 comprises a transformer secondary winding 61 across whose terminals is connected a slidewire resistance 88 by conductors 69 and 10. A slider 1|, connected to the conductor 52 cooperates with the resistance 88 and this slider and resistance form a main controller unit which is operated and positioned in accordance with the absolutepressure existing in the intake manifold For this purpose opposed bellows 12 and 13 are supported adjacent the slider 1| and have their free ends connected thereto as at 14. One bellows 12 is connected by a pressure take-off duct 15 to the intake manifold ll, or other suitable point on the induction system of the engine, while the other bellows 13 is evacuated and compensates in well known manner for atmospheric pressure changes. The rise and fall of the pressure in the intake manifold will thus obviously position the slider 1| along the resistance 68.

Another slidewire resistance 16 is connected as `shown across the secondary winding 61 and a slider 11, connected to conductor 53, is arranged to cooperate with this resistance. The resistance and slider form an acceleration compensating controller and for this purpose the slider 11 is arranged to be positioned in accordance with the rate of the acceleration of the turbine 28 by means of any suitable acceleration responsive device 18 connected to the turbine shaft 19. This device 18 may be of the type shown in my sole application previously referred to, and sufce it to say herein that this device is operative to retain the slider 11 in the position shown as long as the turbine rotates at a certain speed. Should the turbine accelerate sharply the slider 11 will be moved to the right along the resistance 18. A contact provides a dead spot on which the slider 17 normally rests so that minor acceleration of the turbine will have no eect on the control system. i

The network 58 comprises a multi-tapped transformer secondary winding 8l. A slidewire resistance 82 is connected by conductors 84 and 83 to the left-hand terminal of the winding and an adjacent tap thereon. A slider 85 connected to the conductor 53 cooperates with the resistance 82 to provide a velocity or overspeed compensating controller. The slider 85 is accordingly positioned in accordance with the speed of the turbine by means of any'suitable velocity responsive .device 8,8 connected to the turbine shaft 19. A typical such device is described in detail in my sole co-pending application previously mentioned.

The network 50 also includes a slidewire resistance 81 and a slidewire resistance 88 connected at their adjacent ends. One end of resistance 81 is connected by a conductor 83 to the right-hand end of the winding 8|, the junction of the resistances is connected by a conductor 8D to an adjacent tap, and the other end of the resistance 88 is connected by conductor 9| to. a tap between those to which conductors 83 and 98 are connected. A slider 92 connected to the conductor 54 cooperates with the resis- 24- ls positioned. The resistance 88 mayy for the moment be ignored and its function will be later described. v

The various secondary windings 55, 61, and 8|, as well as others later to be described, may all be on the same transformer, which may be the transformer 35 or any other having its primary (not shown) connected to the same source of supply as the primary of transformer 35. To simplify the illustration, the various secondaries have been shownin association with the elements of the system energized by them and to bring out that they may all be parto! the same transformer, the primary winding 93 of transformer 35 has been shown in connection with each secondary winding.` The primary winding 93 may be connected to any suitable source of power, not shown. Regardless of whether the secondary windings 55, 61, and 8| are part of transformer 35 or of other transformers connected to the same source of power, it is evident that the alternating potentials of all of the secondary windings will be in phase with each other and the alternating signal potential applied to the ampliiier input terminals 46 and 41 will be the algebraic sum of the potentials produced in thenetworks y48, 49, and 50.

are of the polarity indicated by the legends in the drawing, are taken as an example, and for a reference potential the conductor 5| leading to the amplifier input terminal 46 is-grounded at 94.

In the network 48 as shown the slider 58 is above the center of resistance 56 and it is accordingly positive with respect to the center tap of the winding 55. On the other hand theslicler is at a center position and hence is negative with respect to this center tap. This network accordingly introduces a potential in the series circuit to the amplier input terminals such that the conductor 52 is at a negative potential with respect to grounded conductor 5|.

In the network 49, the slider 'l1 is obviously positive with respect to the slider 1| and conductor 52 and the potential of slider l1 with 1"espect to ground depends upon the relative magnitudes of the opposing potentials thus introduced by the respective networks 48 and 49. For convenience.

it may be assumed that the positive voltage be- ,tween conductors 53 and 52 introduced by the network 49 is larger than the negative voltage between conductors 52 and 5| from network 48 and that the conductor 53 is thus positive with respect to ground by an amount equal to the difference in such magnitudes.

Considering nally the network 58, it will be evident that the slider 85 is at the same potential as the conductor 53 and being positioned at its extreme right position along the resistance 82, the conductory 83 is at the same potential. The left-hand end of the resistance 81|is so connected by conductor to the winding 8| that it is negative with respect to conductor 83. With the slider 92 in the position shown at ani intermediate point of resistance 81, the conductor 54 is then age between conductor 54 obviously and conductor 53 and the amount of this potential difference will depend sections ofthewinding 8|v between its various taps.A

Now it may be assumed that the negative voltand conductor 53 is equal in magnitude to the positive voltage between conductor 53 and ground and therefore that the compound network, including the three series connected networks 48, 49. and 50 is balanced. Under this condition no signal will be applied to the amplifier 39, no energy will be supplied to the motor field winding 32 and the waste gate 24 will remain stationary. In the positions of the various controls as here shown the waste gate is partially closed and the air compression is at an intermediate value.

Now should the air pressure in the intake manifold I I fall, due for example to an ascent of the aircraft to a higher level, the bellows 12 as it collapses will move the slider 1| to the right along resistance 68 and-increase the magnitude of the previously mentioned positive voltage between conductors 53 and 52. Other factors remaining equal; the terminal 41 of the amplifier 39 will now be negative with respect to the terminal 48 and a signal will be applied to the amplier such as to excite the motor field winding 32 and rotate the motor 29 in the proper direction to move the waste gate 24 toward closed position. This will of course build up the pressure in the intake manifold. At the same time the slider 92 will be moved toward the right along resistance 81 by the gear train 30 and will gradually increase the negative voltage between sliders 92 and 85 to rebaiance the compound network, causing the a new, slightly more closed position. Further details of this operation inresponsreto the differences in pressure will, it is believed, be apparent to those skilled in the art without additional description herein.

In a similar manner, the potentials introduced' into the series circuit will be varied by operation of the sliders 59, 11, and 85. The manual positioning of the slider 59 by knob 60 will permit the balance point of the circuit to be shifted to select the value of manifold pressure to be main- 486,992 hereinbefore mentioned.

In accordance with my present invention I provide also an additional network designated generally at 96 which is connected in series with the compound network including the networks 48, 49, and 50, and which controls the throttle |1 as will now be described in detail.

This network 96 is a bridge circuit having two parallel branches and a pair of input terminals 91 and 98 to which are connected, as shown, the ends of a transformer secondary winding 99 for supplying the bridge with. an alternating potential. One branch of the bridge includes a resistance and a temperature sensing and re- 7 negative with respect to the slider 35 upon the voltages of the 'motor to stop and the .waste gate tote left at 40 gases.

sponsive bulb |0| which is located in the duct Il in such manner as to be exposed to the air supplied the carburetor |8-after such air passes through the after cooler 25. -The bulb |0| is actually la resistance whichvaries in value according to the temperature of this air. The other branch of the bridge comprises a variable re sistance |02, a fixed resistance |03 and another variable resistance |04.

The resistances |00 and I0| are connected in series to form one branch of the bridge extending between the terminals 91 and 98 and from the junction between these resistances there leads a conductor |05 which is connected to an input terminal |06 of an amplifier |01, hereinafter called the throttle amplifier. The resistances |02 and |03 are also connected in series and from their junction leads a conductor |08 which is connected to a slider |09 cooperating with the previously described resistance 88 forming a part of the network 50. This slider |09 and resistance 88 together form a throttle followup or rebalancing potentiometer as will presently appear.

One end of the branch formed by the series connected resistances|02 and |03 is connected to one terminal 98 of the bridge 96 and leading from the other end and the other terminal 91, respectively, are conductors ||0 and IH. The conductor is connected to one end of the resistance |04, which is of the rheostat type, and the conductor I I0 is connected to a slider I |2 which cooperates with the resistance |04 to form an exhaust back pressure controller. Two bellows ||3 and ||4 are supported at opposite sides of the slider ||2. The bellows ||3 is connected by a pressure take-oil duct II5 to the exhaust manifold I2 so that the position of the bellows will directly reflect the pressure of the exhaust The other bellows ||4 is evacuated and serves to compensate for changes in atomspheric pressure.

same will be positioned along the resistance |04 by the exhaust pressure and will insert added resistance into the lower branch of the bridge v96 as this pressure increases.

The amplifier |01 is similar to the amplifier 39 controlling the waste gate and has, in addition tothe input terminal |06 another input terminal ||1 which is connected to the conductor 5| by a conductor ||8. The amplifier |01 controls the operation of a throttle positioning motor ||9 which is connected through a gear train |20 and gears |2| to the throttle |1 and which also operates the follow-up potentiometer slider |09 through a connection to the gear train |20 including, as here shown, the gears |22. The motor ||9 is of the reversible split-phase type, like the waste gate motor 29, having two field windings |23 and |24, displaced in phase by ninety electrical degrees,.and an armature |25. The field winding |23 is energized by one secondary winding |25 of a transformer |21, the energizing circuit being traceable from one end of the secondary winding |28 through a conductor |28, a condenser |29, the eld winding |23 and a conductor |30 back to the other end of winding |28. The- The bellows are connected together and to the slider ||2 as shown at |16 so that the damper is not in closed position.

nected to the common source of supply to maintain proper phase relationships with other parts of the system.

The amplifier |01 supplies the motor .field winding |24 with alternating current potential which either leads or lags the current in the field winding |23 by ninety electrical degrees to cause corresponding opposite rotationof the motor 9. The direction of such rotation depends upon the phase of the signal potential applied to the input terminals |06 and ||1 of the amplifier and this is in turn a function of the balance of the compound network including networks 48, 49 and 50 and bridge 96.

The series excitation circuit for' the throttle amplifier |01 may be traced from its input terminal ||1 through the conductor IIB, the conductor 5|, the network 48, the conductor 52, the network 49, the conductor 53, the network 50, the conductor |09, the'bridge 96, and the conductor |05 to the other input termina1 |06.

I also provide a damper positioning system including a separate bridge circuit |31, an amplifier |38, hereafter called the damper amplifier, and reversible motor |39 which adjusts the damper 28 through a gear train |40.

The bridge |31 comprises two parallel branches 'connected across input terminals 4| and |42 to which are connected the ends of a transformer secondary winding |43. One branch of the bridge comprises a fixed resistance |44 and a temperature responsive resistance bulb |45 which is located in duct |5 in order to be influenced by the temperature of the air supplied to the carburetor I6 after the air passes through the after cooler 25. The resistances |44 and |45 are connected in series across the terminals |4| and |42 and from their junction there leads a conductor |46 to one input terminal |41 of the amplifier |39. The other branch of the bridge comprises a variable resistance |48 connected at one end to the terminal |42 and at the other end connected to one end of a fixed resistance |49 which is connected through conductor |10 to one terminal of a resistance |1| with which cooperates a slider |12. The slider |12 is connected by conductor |13 to terminal |4| and is operatively connected through a shaft |14 to gear train |40. Thus, slider i12 is positioned by motor |39 and cooperates with resistor |1| |31. The junction between the resistances |48 and 149 is connected by a conductor |50 to the other input terminal |5| of the amplifier |38.

to rebalance bridge 1 A switch consisting of switch blades |16 and n |11 is provided for shorting the bridge v96 out of the throttle network when the after cooler Switch blad l?? is fixed while switch blade |16 is movably positioned by a cam 18. Cam |18 is driven through gearing |19 by the gear train |40 and hence by motor 39. Cam |18 is provided with a recessed portion |8| in its cam face which cooperates with a cam follower portion of switch blade |16. Normally, this cam follower portion of switch blade i15 engages the normal raised portion of the cam |18 so that switch blades |16 and |11 are held in contact making engagement against the bias of switch blade |15. Upon the after cooler damper 28 being closed the recessed portion |8| of the cam moves adjacent the cam follower portion of switchblade |16 to permit switch blade |16 to move away from switch blade |11. Switch blade |16 is connected to conductor |08 extending from slider |09 while switch blade 11 is connected to conductor |05 10 extending to terminal |06 of the throttle amplifier so that when switch blades |16 and |11 are engaged, slider |09 is connected directly to the amplifier instead of through bridge 96.

The motor |39 is again of the split phase type having two field windings |52 and |53 displaced by ninety electrical degrees, and an armature |54. One winding |52 is energized by a secondary winding |55 of a transformer |56 and the energizing circuit may be traced from one end of winding |55 through a conductor |51, a phase shifting condenser |58, the field winding |52 and a conductor |59 back to the other end of the secondary winding. The other field winding |53 is energized by the amplifier |38 by conductors |60 and |6|. Another secondary winding |62 on the transformer |56 supplies the amplifie? through conductors |63, and the primary winding |64 of the transformer is again connected to the common source of supply for the entire system.

The secondary windings 99 and |43 for the respective bridges 96 and |31 may be arranged on the associated transformers |21 and |56- or in any other convenient fashion may be supplied with current of the necessary phase relation. For purposes of illustration, primary windings |36 and |64 have been repeated in connection with secondary windings 99 and |43, respectively, to indicate these secondaries as being part of transformers |21 and |56, respectively. through the conductor |46, bridge |31, and the The excitation circuit for the damper amplifier |38 may be traced from its input terminal |41 conductor |50 to the other input terminal |5|.

Operation As has been stated hereinbefore, the heat of compression in the compressor 4 heats the air supplied to the carburetor I6 and to limit this heat and prevent preignition or other undesirable effects in the engine, the after cooler 25 is provided. However, too much cooling is not desirable since, particularly when flying at high altitudes, or at lower levels during the winter months, the temperature of the air at the intake |3 of the compressor will be very low and the air at the carburetor might be so cold as to cause the occurrence of icing conditions.

My system as above described in detail accordingly provides means for regulating the temperature of the air supplied to the carburetor in the manner now to be set out.

It isassumed at the outset that the4 damper 28 in the after cooler intake 26 is closed, as it usually will be when the aircraft takes off. The waste gate 24 is'also assumed to be in a partially closed position, as has been described. With the various elements of the network in the positions previously considered, 83 are positive with respect to the grounded input terminal ||1 of the throttle amplifier just as they are positive with respect to the input terminal 46 of the waste gate amplifier 39. In the case of the waste gate network, this voltage was balanced out by the negative voltage between slider I92 and conductor83. In the case of the throttle network, however, this negative voltage is less since slider |09 is clearly more positive than slider 92. Thus, slider |09 and conductor |08 are positive with respect to the grounded terminal ||1 of the throttle amplifier. This voltage is balanced out by the voltage supplied by the bridge 96 as will be presently explained.

The bridge 96 is initially set up to balance this slider and conductor (with the resistance .|04 at anormal value as i This bridge when balanced obviously will introduce no potential into the series circuit leading from the ampliiier terminal ||1, through the networks 48,.. 48,' and 80 andthrough the bridge 98 to the other inputterminal |08. This being true then, while the bridge yremains in balance,

Q/fthe potential at the amplifier input terminal |08 will be the same as that at.s1ider|09 s'o that the only signal that exists for exciting the throttle vampliiier |01 is that produced bynetworks 48. 49,and 50.`

motor |39 to drive the damper 28 towards open position and therebyl initiate operation of the vafter cooler. As the damper is moved towards lopen position, the slider |12'is moved to the right -so` as to decrease the resistance in the'lower left-hand leg of bridge |91. This compensates Y .for the increase in resistance of the resistor |45 l in the upper right-hand leg so as to rebalance the bridge when the damper 28 reaches a position corresponding 'to-the temperature of bulb |45. I Thereafter, the bridge |31 will remain in control as long as normal flight conditions are encoun- .-tered. 'The eiect of this-bridgeacting through motor |99 is to so position the damper associated with the after cooler as to maintain a constant desired temperature of the air supplied to the Under the conditions assumed. however, the

temperature ofthe air in the duct ills below the desired optimum value. The eiect of this is to make the potential of conductor |08 negative with respect to conductor |08. In other words, the voltage across the bridge is opposite ir/il sense to the voltage between conductor |08 and the i grounded terminal I1 of the throttle amplifier. Under the conditions assumed, this unbalance voltage is exactlyequal to the voltage between conductor |08 and grounded terminal ||1 so that no voltage is impressed upon the input terminals |06 and |1 of the throttle amplifier. The throttle thus remainsv in the position indicated which is intermediate its open and full closed positions. Because of this, the pressure in the intake manifold is less than it would be were the throttle wide open. Since motor 29 positioning the waste gate is controlled by the intake :manifold pressure, it will be obvious that the turbo supercharger is operating to produce a higher ydischarge pressure than would otherwise be neces-l sary were the throttle fully open. Since, the compression of the air causes the same to be heated, the air is warmer than it otherwise would be. In a normal night, this will result in the air rapidly warming up. As it does, the unbalance voltage of the bridge 98 decreases. This has the effect of making input terminal |08 positive with respect to the grounded input terminal ||1 of the throttle amplier. This in turn causes the motor ||9 to be driven in such a direction as to move the throttle towards open position. As the throttle is moved to open position, the arm |09 i's moved to the right or, in other Words, to a more negative position with respect to slider 85. This results in rebalancing of the bridge. As the throttle is thus moved towards open position, the manifold pressure increases. This operates through theintake manifold pressure responsive bellows 12 and slider 1| to move Vthe waste gate towards open position. that is, to decrease the compressing eii'ect of the compressor. Under normal conditions, thiswill continue until the throttle is wide open. In` the operation assumed so far, the bridge |31 has been unbalanced in such a direction as to tend to cause the motor |39 to drive damper 28 towards closed position. Since this damper -is in fully closed position, no movement of the motor was possible. As the temperature of the air leaving the after cooler approaches the value at which the throttle is wide open, however, the Y 'bridge |31 approaches a balanced condition. A'Upon further rise in the temperature of the air, the bridge becomes unbalanced in the opposite direction. This'results in a signal being supplied to the amplifier which is of such phase as to cause `intake manifold. This results in greatly improved control of the output of the engine, in that theeffect of variations in temperature of the air supplied to the carburetor is eliminated.

`As -soon as the damper 28 moves away from closed position, switch blade |18 moves into engagement with switch blade |11. When this hapnpensra-connection is established directly from slider |09 through conductor |08 and a portion of conductor |05 to the input terminal |08 of the throttle ampliiier. In other words, a short circuit is established across the output terminals of the bridge 96 so that further variations in the temperature of element |0| of this bridge will have no effect upon the operation of the throttle motor. The position of the throttle motor will thereafter be determined solely by the bridges 48, 49, and 50.

It will be clear that during normal iiight conditions, the temperature of the air is ordinarily regulated by the arrangement including bridge |31 and after cooler damper motor |39, the after cooler damper 28 being variably positioned to maintain this temperature constant. It is only when the temperature of the air drops to a value at which the after cooler damper 28 vis fully closed that the bridge 96 is permitted to affect the position of throttle motor` and cause -the throttle to assume a partially closed position despite operation of the compressor. Occasionally, conditions may become so extreme that the throttle position which is being maintained for temperature maintenance purposes is such as to cause excessive operation of the compressor. Under these conditions, the pressureof the exhaust gas will rise to a point such as to cause upward movement of slider ||2 with respect to resistor |04. This. increases the resistance in the lower lefty hand leg of bridge 96 so as to have the same effect as; an increase in the resistance of resistor manifold pressure to in turn cause an openingmovement of the waste gate. Thus, the exhaust manifold pressure controller including slider l2 and resistor |04 eiective to act as a limit control to limit the amount of throttle closing movement when-the effect of such movement isA to overload the turbine driven compressor.

The variable resistances |02` and |48 in the respective bridges 06 and |31 -permit the'initial setting up of the balancepoints of these bridges. Adjustment of these -resistances'will have' a simimovement was prevented.

lar effect to that of the variation of the temperature responsive bulbs IUI and H and enables the control points of the bolts to be set at the desired temperature.

In the operation which has been described so far, it is presumed that the setting of the pressure selector network 48 is such as to require the operation of the turbo supercharger. Under some conditions of flight, this will not be required. As the slider 59 of the manual pressure selector 48 is moved upwardly, the potential of conductor 5l and hence the grounded terminal 94 is raised with respect to that of conductor 54 and terminal 4l of the waste gate amplifier. A positive voltageA between terminals 46 and 4l, during the conductive half cycle being considered, results in a voltage being supplied to winding 32 of motor 29 of such phase as to cause the waste gate to be driven towards open position. This, as previously explained, is accompanied by the movement of slider 92 to the left and a resulting increase in the potential of conductor i4 and terminal 41 with respect to conductor 5I and terminal 46. In other words, the movement of slider 92 to the left results in a rebalancing of the bridge. It will be readily apparent that upon slider 59 being moved sufficiently far towards the upper terminal of resistor 56, the waste gate will be in fully open position. Let it be assumed that the conditions are such as not to require movement of the throttle towards closed position in order to heat the air. Under these conditions, the throttle will be in fully closed position at the time that the waste gate reaches open position. During the entire time that the waste gate has been in partially closed position, a voltage has existed between slider IOS and hence terminal |06 of the throttle amplifier with respect to terminal H1, which voltage is of such phase as to tend to run the throttle towards open position. Since the throttle was already in fully open position, however, such Upon the waste gate reaching a fully open position, however, the potentials of slider 92 and |09 become the same and no voltage is impressed on the throttle amplifier. Upon slider 59 of the manual controller 48 being moved farther towards the upper end of resistor 5B to call for still lower manifold pressures, slider 09 becomes positivo during the conductive half cycle being considered, with respect to conductor 5i and hence with respect to terminal ll'l. In other Words, a voltage is impressed on the throttle amplifier which is of such phase as to tend t0 cause the throttle motor to run towards closed position. This in turn causes movement of the slider l il@ to the left. Thus, as long as the damper 28 oi -the the desired temperature, the selection of lower and lower manifold pressures will result in the waste gate being moved to open position and then in the throttle being moved towards closed position. When, however, the damper 28 reaches fully closed position, the bridge 96 is connected into the circuit of the throttle amplifier so as to supply an additional voltage to cause a displacement of the throttle from that position called for by the manual controller 48. Under these conditions, the throttle may be in a partially closed position even though the waste gate be in a fully closed position. This gives the action previously described.

It will be seen that I have provided a novel system for controlling the pressure and temperature of the air supplied to the intake manifold of an internal combustion engine. With my sysafter cooler can maintain the air at tem, the damper ofthe after cooler is so controlled as to maintain the temperature constant. When the requirements for heating of the air are such that they cannot be met by a closing of the after cooler damper, then the throttle is moved towards closed position to compel an increase in the compressing effect of the compressor and thereby to warm the air.

. While I have shown a specific embodiment of my invention, it is to be understood that this is for purposes of illustration only and that my invention is limited solely by the scope of the.

appended claims.

I claim as my invention:

1. In combination, an internal combustion engine having an intake manifold, a compressor for supplying air under pressure to said manifold, a cooler for removing the heat of compression, a throttle for regulating the flow of air from said compressor to said intake manifold, and means responsive to a continuing vreduction in the temperature of the air for first reducing the cooling effect of said coolerv and then increasing the throttling action of said throttle.

2. In combination, an internal combustion engine having an intake manifold, a compressor for supplying air under pressure to said manifold, a cooler for removing the heat of compression, a throttle for regulating the flow of air from said compressor to said intake manifold, means responsive to a continuing reduction in the temperature of the air for rst reducing the cooling effect of said cooler and then increasing the throttling action of said throttle; and means for increasing the compressing effect of said compressor upon such an increase in the throttling action of said throttle.

3. In combination, an internal combustion engine having an intake manifold, a compressor for supplying air under pressure to said manifold, a cooler for removing the heat of compression, a throttle for regulating the flow of air from said compressor to said intake manifold, means responsive to the pressure of the air supplied to said intake manifold for regulating the position of said throttle, means responsive to the temperature of said air for regulating said cooler so as to tend to maintain said air at a predetermined temperature, and means responsive to the temperature of saidair effective when said temperature drops to a value below said predetermined temperature to move said throttle to a position more nearly closed than called for by said pressure responsive means.

4. In combination, an internal combustion engine having anv intake manifold, a compressor for supplying air under pressure to said manifold, a cooler for removing the heat of compression, a throttle for regulating the flow of air from said compressor to said intake manifold, means responsive to the pressure of the air supplied to said intake manifold for regulating the position of said throttle, means responsive to the temperature of said air for regulating said cooler so as to tend to maintain said air at a predetermined temperature, means responsive to the temperature of said air effective when 'said temperature drops to a value below said predetermined temperature to move said throttle to a position more nearly closed than called for by said pressure responsive means, and means to prevent said last named means from aifecting the position of said throttle until said cooler is rendered completely ineffective to cool said air.

5. In combination, an internal combustion engine having an intake manifold, a compressor for supplying air under pressure to said manifold, a cooler for removing the heat of compression, a throttle for regulating the flow of air from 'said compressor to said intake manifold, means responsive to the pressureof the air supplied to said intake manifold for regulating the position of said throttle, means responsive to the tempera'- ture of said air for regulating said cooler so as to tend to maintain said air at a predetermined temperature, and means responsive to the temperature of said air to shift the control point of said pressure responsive means in the direction of throttle closed position.

6. Apparatus for controlling the pressure and temperature of the air supplied to the intake manifold of an internal combustion engine having an engine exhaust driven compressor for supplying `the air and a throttle controlling the flow of air tothe manifold: comprising in combination, means for controlling the compressing effect of the compressor in accordance with a pressure condition affected by said compressor, and means for moving the throttle towards closed position upon a decrease in the temperature of the air supplied to the intake manifold to thereby call for an increase inthe compressing effect of the compressor to heat the'air by the heat of compression, said last mentioned means including means responsive to the pressure of the exhaust for limiting the control of the air temperature over said throttle.

7. Electrical apparatus for controlling the pressure and temperature of the air supplied to the intake manifold of an internal combustion engine having a compressor and turbine driven by ex-f haust pressure, and a throttle controlling the flow of air from compressor to manifold, comprising in combination, means for controlling the compressing eftect of the compressor, electrical means for adjusting said compressing effect controlling means, means including an electrical circuit for controlling said electrical means to vary the compressing effect of the compressor in accordance with the pressure in the intake manifold of the engine, means for Apositioning the throttle, means comprising another electrical circuitincluding a part ofthe previously named circuit and having a part responsive to the temperature of the air supplied by the compressor for adjusting the throttle positioning means and thereby varying the pressure in the manifold and influencing the operation of said compressing eiect controlling means, and said last mentioned electrical circuit including also a means responsive to the exhaust pressure of the engine for limiting the inuence of said circuit over the compressing eiect con'- trolling means.

8. Apparatus for controlling the pressure and temperature of the air supplied to the carburetor of an internal combustion engine of the type having a compressor for supplying such air and a cooler for cooling the air after compression, cornprising in combination, means for adjusting the compressing effect of the compressor in accordance with the pressure of the air supplied to the carburetor, throttling means responsive to the temperature of this air falling below a certain value for throttling the air supplied to the carburetor and calling for a compensating increase in the compression effect of the compressor to thereby heat the air by the added heat of compression, and separate means responsive to an increase in temperature of the air above said y ture of this air below a 16 certain value for setting the cooler into operation` to cool=the air.

9. Apparatus for controlling the pressure and temperature of the air supplied to the intake manifold of an internal combustion engine of the type having a compressor for supplying such air, throttling means forcontrolling the flow oi' air to the manifold, and a cooler for cooling the air after compression, comprising in combination, means for `adjusting the compressing effect of the compressor in accordance with the pressure of the air supplied to the manifold, means for so positioning the throttling means in response to a decrease' in temperature of this air below a certain value as to throttle the air supplied to the manifold and therefore cause said adjusting means to call for a compensating increase in the compressing effect of the compressor to thereby heat the air by the added heat of compression, and separate means responsive to an increase in temperature of the air above said certain value for adjusting the cooler to cool the air.

10. Electrical apparatus for controlling the pressure and temperature of the air supplied to' the intake manifold of an internal combustion engine of thetype having a'compressor for supplying such air, throttling means for controlling the admission of the air to the manifold, and a cooler for cooling the air after compression, comprising in combination, means for adjusting the compressing effect of the compressor in accordance with' the pressure of the air supplied to the manifold, means for so positioning the throttling means in response to the decrease in the temperacertain value as to throttle the air supplied to the manifold and initiate a compensating increase in the compression ratio of the compressor to thereby heat the air by the added heat of compression, said positioning4 means for said throttling means being operative to remove the throttling effect when the temperature of-'the air exceeds said certain value, and other electrical means operative when the temperature of the air exceeds said certain value for adjustingthe said co01er`\-to cool the air.

11. Apparatus for controlling the pressure and temperature of the air supplied to the intake manifold of an internal combustion engine of the type having a compressor for supplying the air, a throttling means for controlling the flow of the air from compressor to manifold, and a cooler for cooling the air after compression, comprising in combination, means for adjusting the compressingeect of the compressor in accordance .with the pressure of the air supplied to the manilow a certain value as to throttle the air supl plied to the manifold and thus cause said adjusting means to call for a compensating increase in the compressing eiect of the compressor to heat the air by the added heat of compression, the said cooler having a damper' for adjusting its cooling effect on the air, and means operated in response to an increase in the temperature of the air above said certain value for opening said damper.

l2. Electrical apparatus for controlling the pressure and temperature of the air supplied to the -intake manifold of an internal combustion engine of the type having a compressorrfor supplying the air, a throttle for controlling the ad- Vmission of the vair to the manifold, and a cooler for cooling the air after compression, comprising in, combination, means for adjusting the compressing eiect of the compressor in accordance with the pressure of the air supplied to the manifold, means for so positioning the throttle as thc temperature of this air falls below a certain value as to reduce the admission of the air to the manifold and therefore cause said adjusting means to call for a compensating increase in the compressing effect of the compressor to heat the air by the added heat of compression, the said cooler having a damper for controlling the ow of fresh air therethrough and thereby adjusting its cooling effect on the air supplied to the manifold, electrical motor means for adjusting the damper, and means responsive to the temperature of the air supplied to the manifold for opening said damper when the temperature exceeds said certain Value.

HUBERT T. SPARRO'W,

i@ REFERENCES CITED 5 UNITED STATES PATENTS Number Name Date 1,371,444 Sherbondy Mal. 15, 1921 2,275,317 Ryder Mar. 3, 1942 i 2,305,810 Mller Dec. 22, 1942 i@ 2,353,201 Taibot July 11, 1944 2,372,272 Helmore Mar. 27, 1945 2,376,143 Edwards et al. May 15, 1945 2,383,563 Pugh et al. Aug. 28, 1945 2,388,350 Taylor Nov. 6, 1945 l5 2,403,398 Reggio July 2, 1946 FOREIGN PATENTS Number Country Date 458,350 Great Britain Dec, 17, 1935 Certiicate of Correction Patent N o. 2,474,018 June 21, 1949 HUBERT T. SPARROW It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 50, for the Word form read from column 10, line 32, strike out through the conductor 146, bridge 137, and the and insert the same in line 34, after 147;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Ofce.

Signed and sealed this 7th day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

